The present invention relates to a supporting apparatus for an optical unit which is stably supported on a slider, the optical unit being consisted of components such as a light source and a reflector which reciprocate to scan and expose an original set on a contact glass.
To accomplish overall reduction in size and increase in operating speed of a picture image forming apparatus, there has been conventionally provided a number of apparatuses, in which an optical unit consisting of components such as a light source and a reflector disposed under a fixed glass is caused to reciprocate to scan and expose an original set on the contact glass.
A structure in which an optical unit is caused to reciprocate in such manner as above includes the following for example; wherein a sliding member is installed under both ends of a first supporting frame body which supports a light source, a concave mirror to converge the light irradiated from the light source and other components, and a second supporting frame body which supports a plane reflector to reflect the reflected light from the original and other components. The sliding member employs a small piece which slides over the slider. A sliding member at each end of the supporting frame body is supported on the rail-like slider. At each end of the supporting frame body is connected a driving wire and the driving force is transmitted to both sides of the supporting frame body through this driving wire (U.S. Pat. Nos. 4,332,460 and 4,353,643).
With the above construction, because the height of the supporting frame body can not be adjusted with respect to the slider, it may become impossible to correct dimensional errors of such components as the supporting frame body and/or slider or errors caused during assembly, so as not to maintain the horizontality of the supporting frame body. Under this condition, the intensity of the light irradiated to an original may not be uniform, or the position of the light reflected from the original and condensed on a photosensitive drum may shift causing to generate a shade on a picture image formed on a copying paper, or the focus of the picture image may become fuzzy or otherwise the picture image may be distorted.
Then, an apparatus is suggested, in which the horizontality of the supporting frame body is adjustable by adjusting the protruding length of each of the sliding member of above disposed under the supporting frame body. More specifically, each sliding member is mounted on the tip of the screws which vertically pass through both ends of the supporting frame body. By turning these screws, the protruding length of each sliding member disposed under the supporting frame body can be adjusted (Japanese Unexamined Utility Model Publication No. 138932/1983). By making adjustments in such manner as above, not only the supporting frame body but also the optical member mounted thereon can be maintained horizontally.
However, in the construction of above, because there are several screw members which need a number of adjustments to be made, it takes time to make adjustments to maintain the supporting frame body horizontally. In addition, there is a problem which requires extra handling such as paint locking to prevent the screw member from becoming loose after an adjustment is once made. Furthermore, because screwing and unscrewing from above are employed, it becomes necessary to remove the contact glass, which affects the workability.
By the way, if one tries to support the supporting frame body on the slider using sliding members, normally at least three sliding members become necessary. To put it in another word, a pair of sliding members to slide over one slider and one sliding member to slide over the other slider will be necessary, and it is preferable that the pair of sliding members to slide over one slider of above are disposed at a wide gap because such arrangement can maintain the stability while the supporting frame body is moving. When the supporting frame bodies having above sliding members are placed respectively at its home position, the gap between both supporting frame bodies can not be made too small because the gap of the pair of the sliding members is wide and such arrangement as this causes a picture image forming apparatus to become large in size. Another problem involved in the above arrangement is that if one tries to reduce the gap between both supporting frame bodies of the above to prevent the picture image forming apparatus from becoming large in size, the stability is affected while the supporting frame bodies are moving and the quality of the picture image obtained will be deteriorated because the gap between the pair of sliding members of the above must also be reduced.
Even in the event the supporting frame bodies are placed at their home positions, there is a suggested structure of which the gap between both supporting frame bodies can be reduced. The suggested structure comprises two sliders disposed above and below, one of which supports the first supporting frame body slidably and the other of which supports the second supporting frame body slidably (Japanese Unexamined Patent Publication No. 37670/1983). In an apparatus with such structure as above, it has an advantage wherein even if the gap between a pair of sliding members on one side and/or on both sides of respective supporting frame bodies is expanded, both supporting frame bodies can be caused to be closer as much as possible at their home positions. However, because the sliders are disposed at two stages of above and below, idle spaces will increase in vertical direction, the picture image forming apparatus will become large, and the slider structures will also become complicated, all of which result in cost increase.
The first object of the present invention is to provide a supporting apparatus for optical unit wherein the horizontality of the supporting frame body mounted with the optical unit can be easily adjusted without removing the contact glass.
The second object of the present invention is to provide a supporting apparatus for optical unit in which the stability in moving of the supporting frame body is improved, and by causing both supporting frame bodies to be closer at their home positions, the reduction of size of the picture image forming apparatus can be achieved.
The first object of above can be accomplished by providing the supporting apparatus for optical unit described hereunder: wherein the supporting apparatus for optical unit comprises a reciprocatingly movable supporting frame body mounted with a light source to illuminate the original on the contact glass, and a reciprocatingly movable supporting frame body mounted with a reflecting mirror to reflect a light reflected from the original, sliding members provided on both ends of at least one of the supporting frame body of above, and an eccentric cam mechanism provided at one end of the supporting frame to make vertical adjustments of one sliding member provided at the same end.
By the structure of the above, sliding members are installed on both sides of reciprocatingly movable supporting frame bodies mounted with optical units, and one of the sliding members is vertically adjustably installed on the supporting frame body by means of the eccentric cam mechanism, and therefore, one end of the supporting frame body where the aforementioned vertically adjustable sliding member is installed can be adjusted to a desired height only by handling the eccentric cam mechanism. Thus it becomes possible to adjust horizontality of the supporting frame body as well as the optical unit mounted on the supporting frame body. Moreover, because the eccentric cam mechanism can be manually operated from transverse direction, there is no necessity to remove the contact glass for adjustment.
In addition, in the supporting apparatus for optical unit according to the present invention, it is preferable that a pair of sliding members are installed on both ends of the above supporting frame bodies, so that the sliding members of either one of the pairs can be vertically adjusted by means of the eccentric cam mechanism and the pair can be freely rotated about an eccentric shaft.
In such a case, by operating the eccentric cam mechanism it becomes possible to adjust horizontality of the supporting frame body and also adjust horizontality of the optical unit mounted on the supporting frame, and by rotation of the sliding members of either one of the pair about the eccentric shaft, two pairs of sliding members come in continuous contact with the top surface of respective sliders. Therefore, it is possible to always maintain a condition wherein the sliding members are supported continuously on the sliders.
In the optical unit supporting apparatus according to the present invention, a pair of sliding members may be mounted on one end of the supporting frame body, and one sliding member may be provided on the other end of the supporting frame body vertically adjustably by means of an eccentric cam mechanism.
In the case of above, by operating the eccentric cam mechanism horizontality of the supporting frame body can be adjusted and horizontality of the optical unit installed on the supporting frame can also be adjusted, and by means of a total of three sliding members, of which a pair of sliding members are installed on one end of the supporting frame body and the remaining one is installed on the other end thereof, it is possible to always maintain a condition wherein the sliding members are continuously supported on the sliders.
The second object of above can be accomplished by providing the optical unit supporting apparatus of the following: there are provided a reciprocatingly movable supporting frame body mounted with a light source to illuminate the original on the contact glass, and a reciprocatingly movable supporting frame body mounted with a reflecting mirror to reflect the light reflected from the original, wherein one end of either one of the supporting frame bodies is provided with a pair of sliding members having relatively large gap therebetween, the other end thereof is provided with a pair of sliding members having relatively small gap therebetween or with one sliding member, the end of the other supporting frame body on the same side of the above one end is provided with a pair of sliding members having relatively small gap therebetween or with one sliding member, and the reverse end thereof is provided with a pair of sliding members having relatively large gap therebetween.
By a structure such as above, on the upper surface of one slider are supported a pair of sliding members having relatively large gap mounted on one supporting frame body and a pair of sliding members having relatively small gap mounted on the other supporting frame body or one sliding member, on the upper surface of the other slider are supported a pair of sliding members having relatively small gap mounted on one supporting frame body or one sliding member, a pair of sliding members having relatively large gap mounted on the other supporting frame body, and both supporting frame bodies can thus be caused to come closer at their home positions. By expanding the gap between a pair of sliding members mounted on each supporting frame body, the stability in moving can be secured.
Features of the present invention will be more apparent in the following description and by referring to the accompanying drawings.